chore(deps): update terraform terraform-ibm-modules/cos/ibm to v8.15.15 (#191)

Author: terraform-ibm-modules-ops

examples/complete/main.tf

@@ -17,7 +17,7 @@ module "resource_group" {
 # Create COS instance
 module "cos_instance" {
   source                 = "terraform-ibm-modules/cos/ibm"
-  version                = "8.15.13"
+  version                = "8.15.15"
   cos_instance_name      = "${var.prefix}-cos"
   kms_encryption_enabled = false
   retention_enabled      = false